Nanofiber composite material having both ultrafine harmful substance filtration performance and air permeability, and manufacturing method therefor

Abstract

A high-air-permeability and high-barrier nanofiber composite material of the present invention comprises an electrospun nanofiber membrane layer, a fiber-structure support layer and an adhesive layer between the nanofiber membrane layer and the support layer, wherein the basis weight of the electrospun membrane layer is 1.0-12 g per 1 m2, the adhesion area ratio between the nanofiber membrane layer and the fiber-structure support layer is 60% or less, the air permeability is 2.0-40 mm / s, and the bacterial and viral filtration efficiency is 99% or higher.

Description

Nanofiber composite material with both ultrafine harmful substance filtration performance and breathability and method for manufacturing the same

[0001] The present invention relates to a nanofiber composite material having both a high level of ultrafine harmful substance filtration performance and breathability, and a method for manufacturing the same.

[0002] Due to recent technological advancements and environmental pollution, the number of substances requiring blocking or filtering in modern society is increasing. For example, the need to block and filter not only fine dust and ultrafine dust but also various types of viruses and bacteria that are periodically prevalent is increasing.

[0003] To block and filter these fine pollutants, active research and development is underway on filter and membrane materials with small pores. While materials with smaller pores are required to filter even smaller particles, their focus on blocking and filtration performance can reduce breathability, leading to reduced filtration speed and energy efficiency.

[0004] In particular, products such as protective clothing, air filters, and medical respiratory filters that must block and filter ultra-fine biological pollutants such as viruses and bacteria all face difficulties if air permeability is low. In the case of protective clothing, the comfort is reduced, making it impossible to wear for long periods of time. In the case of air filters, the pressure difference increases, which can reduce filtration efficiency or cause structural damage to the filter. In the case of respiratory filters, their use is not permitted due to safety issues. In particular, viruses are nano-sized, much smaller than 1㎛, and reducing the pore size to filter them inevitably leads to a decrease in air permeability. Therefore, for application in these product groups, it is essential to develop materials that possess a certain level of blocking and filtration performance that can ensure safety from ultra-fine pollutants, as well as breathability.

[0005] Nanofiber membranes manufactured by electrospinning possess excellent ultrafine particle filtration performance due to their structural characteristics consisting of fibers with diameters in the nanometer range. The fibrous structure of these nanofiber membranes offers the advantage of enhanced breathability compared to other types of membranes. However, as filtration performance is enhanced by decreasing pore size or increasing nanostructure density, breathability decreases significantly. Therefore, to manufacture membranes that simultaneously possess both breathability and ultrafine particle filtration performance, increasing nanostructure density beyond the required level is not necessary as long as a certain level of filtration performance is maintained. In other words, a technology to control the membrane nanostructure that simultaneously possesses a certain level of ultrafine particle filtration performance and breathability is required, and this can be achieved by quantitatively setting the necessary factors in the electrospinning process conditions for manufacturing nanofiber membranes.

[0006] In addition, since nanofiber membranes are very thin by nature, it is desirable to use them in combination with fiber structure supports such as non-woven fabrics, woven fabrics, knitted fabrics, and meshes to create composite materials to improve processability, etc. In order for these composite materials to simultaneously possess ultrafine particle filtration performance and breathability, it is necessary to consider the influence of not only the nanofiber membrane but also the fiber structure used in the composite. In particular, the adhesive used when attaching the nanofiber membrane and the support may block the pores of the membrane, causing a problem of reduced air permeability. In addition, it is necessary to quantitatively limit the application or bonding area of ​​the adhesive within the limit of maintaining the adhesion durability of the membrane and the fiber structure.

[0007] Conventional nanofiber membranes have often been used as a replacement for outdoor waterproof and breathable films. However, to improve the waterproofness of nanofiber membranes, which are vulnerable compared to waterproof and breathable films, and to strengthen the durability of their attachment to supports, the nanostructure density of the electrospun membrane has been excessively increased or excessive adhesives have been used. This has resulted in the loss of the inherent characteristics of nanofiber membranes, namely breathability. Therefore, if nanofiber membrane composites are manufactured using existing methods, they cannot be applied to products such as protective clothing fabrics, air filters, and medical respiratory filters, which require selective blocking performance, i.e., the ability to pass air while filtering ultrafine particles. Therefore, by quantitatively determining the factors mentioned above, it is possible to secure a manufacturing technology for nanofiber composite materials that can be applied to products that simultaneously possess breathability and filtration performance.

[0008] The purpose of the present invention is to provide a highly breathable nanofiber composite material capable of blocking microscopic harmful substances such as ultrafine dust, viruses, and bacteria with high efficiency.

[0009] Another object of the present invention is to provide a nanofiber composite material having excellent breathability and high barrier properties while exhibiting excellent ultrafine harmful substance filtration efficiency.

[0010] The high-barrier nanofiber composite material according to the present invention comprises an electrospun nanofiber membrane layer, a fiber structure support layer, and an adhesive layer between the nanofiber membrane layer and the fiber structure support layer, and is characterized in that the basis weight of the nanofiber membrane layer is 1.0 to 12 g per ㎡, and the air permeability of the nanofiber composite material is 2.0 to 40 mm / s.

[0011] In one embodiment of the present invention, the fiber structure support layer of the high-barrier nanofiber composite material may be characterized by being a nonwoven fabric, a fabric, a knitted fabric, or a mesh.

[0012] In a high-barrier nanofiber composite material according to one embodiment of the present invention, the nanofiber membrane layer may be characterized by including one or two or more selected from polyurethane, thermoplastic polyurethane, polyvinylidene fluoride, poly(vinylidene fluoride-hexafluoropropylene) copolymer, nylon, polyacrylonitrile, polyethersulfone, polysulfone, polyvinyl alcohol, polylactic acid, polyglycolic acid, poly(lactic acid-glycolic acid) copolymer, plicaprolactone, and polyethylene terephthalate.

[0013] In a high-barrier nanofiber composite material according to one embodiment of the present invention, the nanofiber composite material may be characterized in that the filter filtration efficiency is 99.9% or more, and the resulting pressure loss is 30 mmH2O or less.

[0014] The present invention also provides a method for producing a high-barrier nanofiber composite material, and the method for producing a high-barrier nanofiber composite material according to the present invention comprises the following steps: a first step of producing an electrospun nanofiber membrane layer;

[0015] A second step of bonding the nanofiber membrane layer and the fiber structure support layer is included;

[0016] In the second step, the bonding area between the nanofiber membrane layer and the fiber structure support layer is limited to 60% or less of the total area of ​​the composite material.

[0017] The high-barrier, high-pressure nanofiber composite material according to the present invention comprises an electrospun nanofiber membrane layer, a fiber structure support layer, and an adhesive layer between the nanofiber membrane layer and the fiber structure support layer, wherein the basis weight of the electrospun membrane layer is 1.0 to 12 g per ㎡, and the air permeability of the nanofiber composite material is 2.0 to 40 mm / s, thereby efficiently blocking ultrafine harmful substances such as ultrafine dust, viruses, and bacteria, and at the same time exhibiting excellent breathability.

[0018] Figure 1 shows the application area of ​​an adhesive in a high-barrier nanofiber composite material according to one embodiment of the present invention, confirmed through a SEM (Scanning Electron Microscope).

[0019] Advantages and features of embodiments of the present invention, and methods for achieving them, will become clearer with reference to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms. These embodiments are provided only to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

[0020] When describing embodiments of the present invention, detailed descriptions of known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the invention. Furthermore, the terms described below are defined in light of their functions in the embodiments of the present invention and may vary depending on the intent or custom of the user or operator. Therefore, their definitions should be based on the overall content of this specification.

[0021] The pain-resistant and high-barrier nanofiber composite material according to the present invention comprises an electrospun nanofiber membrane layer, a fiber structure support layer, and an adhesive layer between the nanofiber membrane layer and the fiber structure support layer.

[0022] The basis weight of the nanofiber membrane layer is 1.0 to 12 g per ㎡,

[0023] The nanofiber composite material is characterized by having an air permeability of 2.0 to 40 mm / s.

[0024] The high-barrier nanofiber composite material according to the present invention has the advantage of efficiently blocking ultrafine dust, viruses, bacteria, etc., while also exhibiting excellent breathability.

[0025] At this time, the fiber structure support layer may be characterized by being a nonwoven fabric, woven fabric, or knitted fabric or mesh, and specifically, when the support layer is a nonwoven fabric, it may be manufactured from one or more selected from polyethylene, polypropylene, and polyethylene terephthalate, and in order to secure the breathability of the entire nanofiber composite material, a nonwoven fabric having an air permeability of 60 mm / s or more may be used. When the support layer is a woven fabric, a fabric having a warp or weft density of 50 T or less may be used, and when the density of one of the warp or weft yarns is 50 T or less and the density of the other warp or weft yarn is 150 T or less, excellent air permeability can be secured. That is, when the support layer is a woven fabric, the warp or weft yarn satisfies 50 T or less, preferably 20 to 50 T, so that excellent air permeability can be secured while firmly supporting the nano membrane. If the support layer is a knitted fabric, either the WPI (Wales per inch) or CPI (Course per inch) can be less than 70, preferably less than 50, and if this is satisfied, excellent breathability can be ensured.

[0026] The nanofiber membrane layer may specifically include one or more selected from polyurethane, thermoplastic polyurethane, polyvinylidene fluoride, poly(vinylidene fluoride-hexafluoropropylene) copolymer, nylon, polyacrylonitrile, polyethersulfone, polysulfone, polyvinyl alcohol, polylactic acid, polyglycolic acid, poly(lactic acid-glycolic acid) copolymer, plicaprolactone, and polyethylene terephthalate, and may specifically be manufactured by spinning an electrospinning solution containing the above-described polymer. The electrospinning solution may be manufactured by dissolving the above-described polymer in a solvent at a concentration of 10 to 25 wt%, and the solvent used for electrospinning may use one or more selected from dimethylformamide, acetone, chloroform, dimethyl sulfoxide, dimethylacetamide, methyl ethyl ketone, water, alcohol, and acetic acid.

[0027] At this time, the nanofiber membrane layer may have a basis weight of 1 g to 12 g per ㎡, preferably 3 to 10 g per ㎡, to ensure breathability. If the basis weight is too low, the filtration effect of ultrafine substances may be reduced, and if the basis weight is too high, a rapid decrease in breathability may occur.

[0028] An adhesive can be used to attach a nanofiber membrane and a support, and a polyurethane adhesive can be preferably used. In terms of the manufacturing method, the adhesive can be applied to 60% or less, and preferably 20 to 50% of the total area of ​​the nanofiber composite material. In the case of thermal bonding or ultrasonic bonding methods that do not use an adhesive, the bonding area can also be 60% or less, and preferably 20 to 50% of the total area. By satisfying this area range, the problem of pores being blocked by the bonded portion and reduced breathability can be prevented. In addition, the shortest distance between the bonded portion and the adjacent bonded portion can be 3 mm or less, and preferably 1.5 mm or less, and by satisfying this range, excellent breathability can be secured while uniformly bonding the entire nanofiber composite material.

[0029] According to one embodiment of the present invention, the high-barrier, high-pressure nanofiber composite material has an air permeability of 2.0 to 40 mm / s, preferably 10 to 20 mm / s, measured at a unit area of ​​38 ㎠ and a pressure of 100 Pa in accordance with KS K ISO 9237, which is an advantage of significantly improved air permeability compared to commercial Gore-Tex. In addition, the high-barrier, high-pressure nanofiber composite material according to one embodiment of the present invention has a filter filtration efficiency of 99% or more as measured by ISO 29463-3, and at the same time, a pressure loss of 25 mmH2O or less, and also has the characteristics of virus and bacteria filtration efficiencies of 99% or more, respectively.

[0030] The present invention also provides a method for producing a high-barrier nanofiber composite material, and the method for producing a high-barrier nanofiber composite material according to the present invention comprises the following steps: a first step of producing an electrospun nanofiber membrane layer;

[0031] A second step of bonding the nanofiber membrane layer and the fiber structure support layer is included;

[0032] In the second step, the bonding area between the nanofiber membrane layer and the fiber structure support layer is limited to 60% or less of the total area of ​​the composite material.

[0033] In the method for manufacturing a high-barrier, high-pressure nanofiber composite material according to the present invention, the bonding area ratio can be determined by the following relational expression 1, and can be bonded in a certain pattern shape such as a dot, a cross, a grid, a diamond, etc., but the pattern of the bonding portion can be freely selected if the bonding area ratio is satisfied. Specifically, the bonding area observed in a arbitrarily selected 5×5mm unit area can be regarded as the same as the entire bonding area, and in detail, the difference between the bonding area ratio of a arbitrarily selected 5×5mm unit area and the bonding area ratio of the entire nanofiber composite material can be 10% or less.

[0034] [Relationship 1]

[0035] Adhesion area ratio (%) = (Area of ​​the adhesive portion between the nanofiber membrane layer and the fiber structure support layer ÷ Total area of ​​the composite material) × 100

[0036] In addition, when using an adhesive, the adhesive can be applied in an amount of 3 g or less, preferably 2 g or less, per 1 m2 of nanofiber composite material while satisfying the above-described adhesive area ratio, and within this range, the problem of the adhesive blocking the pores of the nanofiber membrane can be prevented and excellent adhesiveness can be secured.

[0037] The high-barrier nanofiber composite material manufactured by the present invention has the characteristic of being able to filter fine particles such as fine dust, viruses, and bacteria with an efficiency of 99% or more, while also having excellent breathability, making it usable in various fields such as clothing, medical products, filters, vents, wires, or cables.

[0038] In addition, the support layer and nanofiber membrane used in the method for manufacturing a nanofiber composite material according to one embodiment of the present invention may use materials identical or similar to those described above.

[0039]

[0040] Hereinafter, the present invention will be specifically described through examples and comparative examples. The examples below are provided solely to aid understanding of the present invention, and the scope of the present invention is not limited by the examples below.

[0041]

[0042] [Manufacturing Examples 1-1 to 1-2]

[0043] A nanofiber membrane was manufactured by electrospinning a thermoplastic polyurethane electrospinning solution to satisfy a basis weight of 4.0 g / ㎡. A polyurethane adhesive (TL5808B, HBFuller Co.) was applied to the manufactured membrane to cover 35% of the total area, and a fabric satisfying the warp and weft densities of the fabric as shown in Table 1 was attached to manufacture a composite material. The air permeability of the manufactured composite material was measured, and the results are shown in Table 1. The air permeability referred to in the present invention is based on the measurement at a unit area of ​​38 ㎠ and a pressure of 100 Pa according to KS K ISO 9237. In addition, the membrane alone in Table 1 is the experimental result of the nanofiber membrane itself satisfying 4.0 g / ㎡, and the Gore-Tex experiment was conducted using commercially available Gore-Tex fabric. In addition, the adhesive application area ratio was calculated based on the results confirmed through SEM (Scanning Electron Microscope) photographs as shown in Fig. 1.

[0044] At this time, the thermoplastic polyurethane electrospinning solution was first prepared by adding thermoplastic polyurethane to a mixed solution of DMF (dimethylformamide) and acetone as a solvent in a volume ratio of 1:1 to obtain a concentration of 15 wt%.

[0045]

[0046] Category 1-11-2 Membrane-only Gore-Tex fabric warp density 74114--fabric weft density 6248--air permeability (mm / s) 1.414.1302.1

[0047] Referring to Table 1, it can be confirmed that the highest air permeability is exhibited when the membrane is used alone. In addition, when comparing Manufacturing Examples 1-1 and 1-2, it can be confirmed that when the warp density and weft density of the fabric are both 50 or more (Manufacturing Example 1-1), significantly lower air permeability is exhibited compared to when either the warp density or the weft density of the fabric is 50 or less (Manufacturing Example 1-2). Accordingly, it can be confirmed that excellent air permeability can be secured when the warp density or the weft density is 50 or less, and it can be confirmed that these air permeability values ​​are approximately 6 to 7 times higher than those of commercially available Gore-Tex.

[0048]

[0049] [Manufacturing Examples 2-1 to 2-3]

[0050] A composite material was manufactured using the same method as Manufacturing Example 1-1, but instead of a fabric, a knitted fabric satisfying the WPI (Wales per inch) and CPI (Course per inch) values ​​in Table 2 below and a nanofiber membrane satisfying the basis weight in Table 2 were used to manufacture the composite material, and the air permeability thereof was measured and shown in Table 2 below.

[0051]

[0052] Category 2-12-22-3 Membrane Single Membrane Basis Weight (g / ㎡) 4.0 7.0 7.0 7.0 Knitted WPI 3613 152 - Knitted CPI 359 440 - Air Permeability (mm / s) 22.9 5.0 1314

[0053] Referring to Table 2, it can be confirmed that the air permeability is greatly improved when the membrane basis weight is low, and in the case of Manufacturing Example 2-3 in which at least one WPI or CPI value is 50 or lower in the knitted fabric, it can be confirmed that the decrease in air permeability is not great compared to the membrane alone.

[0054]

[0055] [Manufacturing Examples 3-1 to 3-3]

[0056] Nanofiber composite materials having a basis weight of 7.0 g / ㎡ of nanofiber membrane and an adhesive area ratio as shown in Table 3 below were manufactured using the same method as in Manufacturing Example 2-3, and the air permeability was measured. The adhesive area ratio as referred to in the present invention refers to a value calculated by the following equation from an electron microscope photograph (Fig. 1) of a unit area of ​​at least 5×5 mm arbitrarily selected from a nanofiber-fiber structure composite material manufactured by evenly bonding in a regularly repeating pattern such as a dot, cross, grid, or diamond, and the adhesive area ratios presented in Table 3 are average values ​​calculated from 10 or more electron microscope photographs selected from arbitrarily different parts of the nanofiber composite material.

[0057] Adhesion area ratio (%) = (Area of ​​the adhesive portion between the nanofiber membrane layer and the fiber structure support layer ÷ Total area of ​​the composite material) x 100

[0058]

[0059] Category 3-13-23-3 Application area ratio (%) 354560 Air permeability (mm / s) 13117

[0060] Referring to Table 3, it can be confirmed that when the bonding area ratio is 50% or less, the air permeability is 10 mm / s or more, and when it is 40% or less, the air permeability is 12 mm / s or more.

[0061]

[0062] Based on the nanofiber composite material of Manufacturing Example 3-2, the bacterial filtration efficiency (BFE), virus filtration efficiency (VFE), and filter filtration efficiency were measured, and the results are shown in Table 4. At this time, the bacterial filtration efficiency was measured using Staphylococcus aureus, and the liquid suspension containing the bacteria was aerosolized and delivered to the filter medium at a constant flow rate of 1 cubic foot per minute. The virus filtration efficiency was measured in the same way as the bacterial filtration efficiency, except that the bacteriophage phiX174 was used. In addition, the filter filtration efficiency was measured based on 0.15 ㎛ NaCl and a face velocity of 5 cm per second according to ISO 29463-3.

[0063]

[0064] Classification BFEVFE Filter Filtration Efficiency Filtration Efficiency Pressure Loss Result 99.9% 99.9% 99.999% or more 25 mmH2O or less

[0065] Referring to Table 4, it can be confirmed that the filtration efficiency for bacteria and viruses is over 99%, and for 0.15 ㎛ particles, the filtration efficiency is over 99.999%, and in the process, the pressure loss is low at 25 mmH2O or less.

Claims

1. It comprises an electrospun nanofiber membrane layer, a fiber structure support layer, and an adhesive layer between the nanofiber membrane layer and the fiber structure support layer. The basis weight of the nanofiber membrane layer is 1.0 to 12 g per ㎡, A nanofiber composite material having a high air permeability and high barrier properties, characterized in that the nanofiber composite material has an air permeability of 2.0 to 40 mm / s.

2. In paragraph 1, A high-barrier, high-performance nanofiber composite material characterized in that the fiber structure support layer is a nonwoven fabric, fabric, knitted fabric or mesh.

3. In paragraph 1, A high-barrier, high-pressure nanofiber composite material characterized in that the electrospun nanofiber membrane layer comprises one or more selected from polyurethane, thermoplastic polyurethane, polyvinylidene fluoride, poly(vinylidene fluoride-hexafluoropropylene) copolymer, nylon, polyacrylonitrile, polyethersulfone, polysulfone, polyvinyl alcohol, polylactic acid, polyglycolic acid, poly(lactic acid-glycolic acid) copolymer, plicaprolactone, and polyethylene terephthalate.

4. In paragraph 1, The above nanofiber composite material has a filter filtration efficiency of 99.9% or more, A high-barrier, high-pressure nanofiber composite material characterized by a pressure loss of 30 mmH2O or less.

5. In paragraph 1, The above nanofiber composite material is a high-barrier, high-efficiency nanofiber composite material characterized by a bacterial and viral filtration efficiency of 99% or more.

6. Step 1 of manufacturing an electrospun nanofiber membrane layer; A second step of bonding the nanofiber membrane layer and the fiber structure support layer is included; A method for manufacturing a high-barrier, high-pressure nanofiber composite material, characterized in that in the second step, the bonding area between the nanofiber membrane layer and the fiber structure support layer is limited to 60% or less of the total area of ​​the composite material.

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